Polonium is the element with the most isotopes. That means that different atoms of polonium have different numbers of neutrons even as they have the same number of protons, which is 84. None of these 33 isotopes is stable.
The isotope with the longest half-life is Po209. Its half life is about 125 years, give or take three years.
All the isotopes of polonium are radioactive. This means the nucleus of the polonium isotopes gives off ionizing radiation such as alpha, beta or gamma rays.
Polonium is a silvery, solid metal or metalloid at standard temperature and pressure, but is very rarely found in nature. It's the result of the decay of bismuth that's found in pitchblende. Polonium serves no purpose in supporting biological processes and has little use in chemistry and industry. Polonium also doesn't form natural compounds.
Marie Curie discovered polonium in 1898 as she strove to find out the cause of the radioactivity in Bohemian pitchblende. Polonium was the first element she discovered, and she named it after her native Poland. Since Poland was divided between Germany, Russia and the Austro-Hungarian Empire at the time, she hoped naming the element after her country would call attention to its plight.